Expression of concern: Systematic investigation on the intracellular trafficking network of polymeric nanoparticles.

Expression of concern for 'Systematic investigation on the intracellular trafficking network of polymeric nanoparticles' by Jinxie Zhang et al., Nanoscale, 2017, 9, 3269-3282, DOI: 10.1039/C7NR00532F.

Expression of concern: Controllable 2H-to-1T' phase transition in few-layer MoTe2.

Expression of concern for 'Controllable 2H-to-1T' phase transition in few-layer MoTe2' by Yuan Tan et al., Nanoscale, 2018, 10, 19964-19971.

Orthogonal dual-modification of proteins for the engineering of multivalent protein scaffolds.

To add new tools to the repertoire of protein-based multivalent scaffold design, we have developed a novel dual-labeling strategy for proteins that combines residue-specific incorporation of unnatural amino acids with chemical oxidative aldehyde formation at the N-terminus of a protein. Our approach relies on the selective introduction of two different functional moieties in a protein by mutually orthogonal copper-catalyzed azide-alkyne cycloaddition (CuAAC) and oxime ligation. This method was applied to the conjugation of biotin and ß-linked galactose residues to yield an enzymatically active thermophilic lipase, which revealed specific binding to Erythrina cristagalli lectin by SPR binding studies.

Controlled thioamide vs. amide formation in the thioacid-azide reaction under acidic aqueous conditions.

The thioacid-azide reaction and its chemoselectivity were probed with alkyl azides for a potential application to form amide bonds in aqueous solvents. Our results reveal that under acidic conditions thioamides were formed as major reaction products suggesting a competing mechanism, whereas reactions forming amides predominated at slightly higher pH values.

Traceless Staudinger acetylation of azides in aqueous buffers.

In this paper, we demonstrate the applicability of water-soluble p-dimethylaminoethyl substituted phosphinomethanethiol in acetyl transfer reactions by the traceless Staudinger ligation with unprotected ε-azido lysine containing peptides in aqueous buffer systems. Additionally, we present an improved synthesis pathway for the water-soluble phosphinothiol linkers requiring less steps in a comparable overall yield in comparison to previously published protocols.

Acidic and basic deprotection strategies of borane-protected phosphinothioesters for the traceless Staudinger ligation.

The traceless Staudinger ligation has recently found various applications in the field of peptide synthesis and modification, including immobilization and cyclization strategies. In this report, we utilize the traceless Staudinger ligation in the formation of amide bonds, which allows the acquisition of acylated aminosugars and peptides as well as the cyclization of peptides. A key element in these synthetic procedures is the use of a borane-protected phosphinomethanethiol, which is demonstrated to be prone towards oxidation in its unprotected form, during the synthesis of phosphinothioesters. In combination with acidic and basic deprotection strategies for the borane-protected phosphinothioesters, amide bonds can be formed in the presence of azides in moderate to good overall yields.